Bituminous sands (also known as oil sands or tar sands are sands that contain sand, clay, water, and a dense and very viscous petroleum known as bitumen. Oil sands are developed through two methods: open-pit mining and deep underground production. In open-pit mining, hot water is employed for separating bitumen from the sand. This water is then sent to a tailings pond. The tailings ponds are an environmental concern. For example, these ponds have been harmful to migrating birds. Efforts are continually being made to recover the heavy oil and bitumen from these tailings ponds and to clean and rehabilitate contaminated bodies of water.
Applicant developed and patented some early skimmer technologies that used a continuous conveyor to skim heavy oil or bitumen.
The first is disclosed in U.S. Pat. No. 5,743,694 (Hines) entitled “Oil Recovery Apparatus”. This patent disclosed an open-mesh conveyor designed to slope from a vessel into the contaminated water and to run with the lower flight of the conveyor travelling inboard over a flat bottomed trough.
An improvement on the technology disclosed in U.S. Pat. No. 5,743,694 is disclosed in U.S. Pat. No. 6,328,888 (Hines) entitled “Skimmer”. The latter patent disclosed a conveyor which utilizes a press roller or other mechanical pusher elements to push the extremely viscous heavy oil or bitumen from the cavities defined by the mesh of the conveyor into a holding tank.
Despite this improvement, very substantial technical challenges remain. Recovering the extremely viscous and sticky bitumen or heavy oil from a contaminated water environment such as a tailings pond is very challenging for a number of reasons. For example, the bitumen or heavy oil adheres to the skimmer mechanism, interfering with the smooth operation of the conveyor and inhibiting discharge from the conveyor. Effective skimming is also highly sensitive to the precise placement and orientation of the skimmer relative to the heavy oil or bitumen floating on the surface of the contaminated water environment. Another problem arises when attempting to transfer bitumen to shore from the holding tank on the barge. Therefore, there exists a need in the oil industry for a more effective skimmer and barge and for more effective methods of skimming bitumen and heavy oil.